Hitherto, in a rolling bearing apparatus for supporting a wheel of an automobile or the like, a sealing device is used for sealing between inner and outer rings to prevent foreign matter such as muddy water from entering the rolling bearing apparatus. Such a sealing device is mounted at each of both ends of a space between the inner and outer rings of the rolling bearing apparatus (e.g., see PATENT LITERATURE 1).
FIG. 4 is a cross-sectional view showing a conventional sealing device mounted at one end side of a rolling bearing apparatus for an automobile. In this drawing, the rolling bearing apparatus 100 includes an inner shaft 101 which is integrally formed with a flange portion 101a for fixing a wheel of the automobile, an inner ring 102 as a rotational ring which is externally fitted and fixed to the inner shaft 101, an outer ring 103 as a fixed ring, and balls 104 as rolling elements.
The sealing device 110 mounted on the rolling bearing apparatus 100 includes: a slinger 111 which is fitted and fixed to the outer peripheral surface of the inner ring 102, extends in a radially outward direction, and is made of a metal; an inner seal member 112 which is mounted at the inner peripheral side of an end portion of the outer ring 103 opposed to the slinger 111; and an outer seal member 113 which is mounted at the outer peripheral side of the end portion of the outer ring 103.
The inner seal member 112 includes a core metal 114 which is internally fitted and fixed to the end portion of the outer ring 103, and a plurality of inner seal lips 115 to 117 which are fixed to the core metal 114 and are in slidable contact with the slinger 111. The plurality of inner seal lips 115 to 117 are formed so as to extend from an inner peripheral end portion of the core metal 114 toward the slinger 111 and are in slidable contact with the slinger 111 which rotates with running of the vehicle, thereby sealing a gap between the inner ring 102 and the outer ring 103 to prevent foreign matter such as muddy water from entering the rolling bearing apparatus 100.
The outer seal member 113 includes a core metal 118 which is externally fitted and fixed to the end portion of the outer ring 103, and an outer seal lip 119 and a labyrinth lip 120 which are fixed to the core metal 118. The outer seal lip 119 is formed so as to extend from an inner peripheral end portion of the core metal 118 toward a side surface of the flange portion 101a and is in slidable contact with the side surface of the flange portion 101a which rotates with running of the vehicle, thereby sealing a gap between the flange portion 101a and the outer ring 103. In addition, the labyrinth lip 120 is formed so as to extend from an outer peripheral end portion of the core metal 118 toward the side surface of the flange portion 101a and forms a labyrinth seal together with the side surface of the flange portion 101a. The outer seal lip 119 and the labyrinth lip 120 prevent foreign matter such as muddy water from entering through the gap between the end portion of the outer ring 103 and the side surface of the flange portion 101a. 